Permanent magnet electric rotating machine and electromotive vehicle using permanent magnet electric rotating machine

ABSTRACT

A magnetic gap is provided between a permanent magnet of a rotor and an auxiliary magnet pole portion which is arranged adjacent to the permanent magnet in a peripheral direction. A gradual change in a magnetic flux density distribution of a surface of the rotor is obtained and a cogging torque and a torque pulsation are restrained. By obtaining a reluctance torque according to the auxiliary magnetic pole, a permanent magnet electric rotating machine in which the cogging torque and the torque pulsation are restrained can be obtained and further an electromotive vehicle having the permanent magnet electric rotating machine can be provided.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a permanent magnet electric rotatingmachine and an electromotive vehicle using a permanent magnet electricrotating machine and in particularly to a permanent magnet electricrotating machine in which permanent magnets are used as a magnetic fluxgenerating means and an electromotive vehicle such as an electricvehicle which uses the permanent magnet electric rotating machine.

2. Prior Art

Up to now as one kind of an electric rotating machine, a permanentmagnet electric rotating machine has been used, in which permanentmagnets of the permanent magnet electric rotating machine are used as amagnetic field generating means for a rotor.

As a conventional permanent magnet electric rotating machine, there is aknown surface magnet structure permanent magnet electric rotatingmachine, wherein plural permanent magnets of the permanent magnetelectric rotating machine are arranged in parallel and fixed on asurface of a rotor and further adjacent permanent magnets are arrangedto have a reversed polarity at a peripheral direction.

However, in the above stated surface magnet structure permanent magnetelectric rotating machine, during a high speed rotation there is apossibility of the permanent magnet peeling off due to centrifugalforce.

A permanent magnet rotor having a permanent magnet embedding structurepermanent magnet electric rotating machine is disclosed in Japanesepatent laid-open publication No. Hei 5-76,146. Namely, in the abovestated permanent magnet rotor, permanent magnets are inserted in andfixed to holes, such holes extend into an interior portion of the rotorin an axial direction.

Further, so as to aim to simplify a structure for a case in which therotor having the permanent magnet embedding structure of the permanentmagnet electric rotating machine is performed to carry out a skewstructure, such a permanent magnet structure of the permanent magnetelectric rotating machine is disclosed in Japanese patent laid-openpublication No. Hei 5-236,687. Namely, in this permanent magnetstructure permanent magnet electric rotating machine, a space is formedfrom an end face of each of the permanent magnets which are installed inan interior portion of a rotor to an outer periphery of the rotor.

However, in the above stated prior art, there is a problem in which anobtaining of a reluctant torque by auxiliary magnetic poles and areduction in a cogging torque or a torque pulsation are notincompatible. Hereinafter, in this specification, the torque pulsationindicates one combining both the reluctant torque and the coggingtorque.

In the permanent magnet embedding structure permanent magnet electricrotating machine, utilizing the rotor member provided between theadjacent permanent magnets as the auxiliary magnetic pole, a compositevector of an armature magnetomotive force of a stator is controlled todirect toward a side of a rotation direction but not to direct toward acentral position direction of the auxiliary magnetic pole, as a result,the reluctant torque can be obtained.

This reluctant torque is added to a main torque generated by thepermanent magnets and the entire torque of the permanent magnet electricrotating machine can be increased. Therefore, the efficiency of thepermanent magnet embedding structure permanent magnet electric rotatingmachine can be increased.

On the other hand, in the conventional permanent magnet electricrotating machine, since the permanent magnets always generate a magneticflux regardless of the existence of an electric power supply, the rotorcan always receive a force. The force is one which corresponds to apositional relationship between the permanent magnet and a stator'ssalient pole portion and during the rotation time the above stated forcechanges in a pulsed manner. This pulsating force appears as the torquepulsation.

This torque pulsation obstructs a smooth rotation of the rotor, thuscausing a problem in which a stable operation of the permanent magnetelectric rotating machine cannot be obtained.

In the permanent magnet rotor of the permanent magnet electric rotatingmachine shown in Japanese patent laid-open publication No. Hei 5-76,146,since the rotor has the auxiliary magnetic poles, it is possible toobtain the reluctant torque. However, since a distance formed betweenthe permanent magnet and the auxiliary magnetic pole is minute in theperiphery direction, an abrupt change in a magnet flux densitydistribution appears in the minute distance portion, accordingly thetorque pulsation arises.

On the other hand, in the permanent magnet electric rotating machineshown in Japanese patent laid-open publication No. Hei 5-236,687, thespace is formed between the adjacent permanent magnets. In this space,an adherence property fill-up member comprised of a non-magnetic body islocated.

Accordingly, the magnet flux density distribution between the adjacentpermanent magnets is muted, such that it hardly generates the coggingtorque or the torque pulsation. However, the above stated space or thefill-up member does not work as the auxiliary magnetic pole, thereforethe reluctant torque can not be obtained.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a permanent magnetelectric rotating machine and an electromotive vehicle using a permanentmagnet electric rotating machine wherein a torque pulsation can berestrained by obtaining a reluctant torque according to auxiliarymagnetic poles.

According to the present invention, a permanent magnet electric rotatingmachine comprises a stator obtained by a winding on a stator iron core,plural permanent magnet insertion holes for forming magnetic pole pieceportions at a side of the stator through auxiliary magnetic poleportions, and a rotor embedding plural permanent magnets in thepermanent magnet insertion holes. The rotor is arranged adjacent to thestator with a rotation air gap.

A magnetic gap is provided between at least one of the permanent magnetsand at least one of the auxiliary magnetic pole portions which isadjacent to at least one of the permanent magnets in a peripheraldirection.

The magnetic gap moderates the change in the magnetic flux densitydistribution in the peripheral direction between the permanent magnetand the auxiliary magnetic pole portion, accordingly thetorque—pulsation can be decreased.

Therefore, the magnetic gap can be formed merely by the space or by thearrangement or the filling-up of the non-magnetic material.

Further, this magnetic gap can be formed at both ends of the permanentmagnets and this magnetic gap can be formed at one end of the peripheraldirection of the permanent magnet complying with a request of therotation direction of the permanent magnet electric rotating machine anda use for applying the permanent magnet electric rotating machine.

However, due to the provision of the above described magnetic gap at theperipheral direction end portion of the permanent magnet, there is apossibility that the positioning of the permanent magnet becomesunstable during the high speed rotation, etc.

For the above stated reasons, according to the present invention, anindented portion is provided at a bottom portion of the permanentmagnet, and on the indented portion the permanent magnet is arranged andinstalled in a stable manner. According to the present invention, anonmagnetic material member is arranged in the magnetic gap.

Further, since the magnetic gap is enough to moderate the is magneticflux density distribution against the stator, by varying the dimensionor the width (space) of the magnetic gap, it is possible to assist thefunctions of the auxiliary magnetic pole portion.

According to the present invention, a peripheral direction width of themagnetic gap at a face of the stator side (an outer peripheral portionof the stator) is formed larger than a peripheral direction width of themagnetic gap at a face of an anti-stator side (an inner peripheralportion of the stator).

According to the present invention, a peripheral direction cross-sectionof the magnetic gap is a triangular shape. Therefore, it is possible tocirculate the magnetic flux of the auxiliary magnetic pole portionsaround the permanent magnets, as a result the large reluctance torque ofthe permanent magnet electric rotating machine can be obtained.

According to the present invention, the magnetic pole piece portion isconnected to the auxiliary magnetic pole portion through a bridgeportion, and a stator side surface and a magnetic gap side surface ofthe bridge portion are formed substantially in parallel. The bridgeportion is formed to extend vertically toward an inclined face of themagnetic gap.

Therefore, it is possible to restrain the magnetic flux leakage from thepermanent magnets and the member of the stator side of the magnetic gapto the auxiliary magnetic pole portions.

Further, according to the present invention, the bridge portion isformed to extend vertically toward an inclined face of the magnetic gap,accordingly the centrifugal force given on the permanent magnet can besupported according to the tensile force of the bridge portion, as aresult a permanent magnet electric rotating machine capable of higherspeed rotation can be obtained.

According to the present invention, a permanent magnet electric rotatingmachine comprises a stator having a winding on a stator iron core,plural permanent magnet insertion holes for forming magnetic pole pieceportions at a side of the stator through auxiliary magnetic poleportions, and a rotor embedded plural permanent magnets in the permanentmagnet insertion holes, the rotor being arranged with respect to thestator with a rotation air gap. A magnetic gap is provided between atleast one magnetic piece portion and at least one auxiliary magneticpole portion.

The above stated magnetic gap can moderate the magnetic flux densitydistribution at the peripheral direction of the rotor between thepermanent magnet and the auxiliary magnetic pole portion.

According to the present invention, the magnetic gap contacts aperipheral direction end portion of a face of a stator side of thepermanent magnet. The magnetic gap extends toward an inner side of thepermanent magnet.

According to the present invention, the magnetic gap extends with arectangular shape toward an inner side of the permanent magnet.Therefore, it is possible to restrain the magnetic flux from leakingfrom the face of the stator side of the permanent magnet to theauxiliary magnetic pole portion.

According to the present invention, a permanent magnet electric rotatingmachine comprises a stator having a winding on a stator iron core,plural permanent magnet insertion holes for forming magnetic pole pieceportions at a side of the stator side through auxiliary magnetic poleportions, and a rotor embedded plural permanent magnets in the permanentmagnet insertion holes, the rotor being arranged with respect to thestator with a rotation air gap.

A magnetic gap is provided between at least one magnetic piece portionand at least one auxiliary magnetic pole portion, and the magnetic polepiece portion is fixed to the auxiliary magnetic pole portion through anon-magnetic magnetic pole piece supporting member.

According to the present invention, the magnetic pole piece supportingmember has a U-shape and the magnetic pole piece supporting member isinserted from both axis of the rotor iron core. Therefore, thecentrifugal force of the permanent magnet given on the magnetic polepiece portion can be supported according to the auxiliary magnetic poleportion.

According to the present invention, a permanent magnet electric rotatingmachine comprises a stator having a winding on a stator iron core,plural permanent magnet insertion holes for forming magnetic pole pieceportions at a side of the stator through auxiliary magnetic poleportions, and a rotor embedded plural permanent magnets in the permanentmagnet insertion holes, the rotor being arranged with respect to thestator with a rotation air gap.

A magnetic gap is provided between at least one magnetic piece portionand at least one auxiliary magnetic pole portion, a permanent magnetsupporting member is arranged between the magnetic pole piece portionand the permanent magnet and the permanent magnet supporting member isassembled according to a magnetic material member and a nonmagneticmaterial member.

The magnetic material of the permanent magnet supporting member isarranged between the magnetic pole piece portion and the permanentmagnet, and the non-magnetic material member of the permanent magnetsupporting member is engaged with the magnetic pole piece portion.Therefore, the supporting force against the centrifugal force acting onthe permanent magnet can be increased.

According to the present invention, a non-magnetic material member isarranged in the magnetic gap. Therefore, the supporting force againstthe centrifugal force given on the permanent magnet can be increased.

According to the present invention, a peripheral direction width of thepermanent magnet is smaller than a peripheral direction width of theauxiliary magnetic pole portion. Therefore, the centrifugal force actingon the permanent magnet can be effectively lessened.

According to the present invention, an electromotive vehicle is drivenby a permanent magnet electric rotating machine. Therefore, theelectromotive vehicle having a small cogging torque and a stable driveapparatus can be provided.

The permanent magnet electric rotating machine according to the presentinvention can be applied to a generator and an electric motor, an innerrotor type and an outer rotor type permanent magnet electric rotatingmachine, a rotary type and a linear type permanent magnet electricrotating machine, a concentric winding stator structure and a salientwinding stator structure permanent magnet electric rotating machine.

The present invention does not depend on the shape of the permanentmagnet, therefore the permanent magnet having a rectangular body, an arcshape, and a trapezoid shape. etc. can be applied and similar effectscan be obtained.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an end cross-sectional view showing one embodiment of apermanent magnet electric rotating machine according to the presentinvention;

FIG. 2 is an enlarged view showing a surrounding portion of an optionalpermanent magnet of a rotor of the permanent magnet electric rotatingmachine shown in FIG. 1;

FIG. 3 is an axial direction cross-sectional view showing one embodimentof the permanent magnet electric rotating machine shown in FIG. 1;

FIG. 4A is a diagram functionally explaining the rotor member of thepermanent magnet electric rotating machine shown according to thepresent invention in FIG. 2;

FIG. 4B is a graph showing a magnetic flux density distribution of arotor member of the permanent magnet electric rotating machine accordingto the present invention shown in FIG. 2;

FIG. 5A is a diagram functionally explaining the rotor member of apermanent magnet electric rotating machine according to the prior art;

FIG. 5B is a graph showing a magnetic flux density distribution of arotor member of a permanent magnet electric rotating machine accordingto the prior art;

FIG. 6 is a cross-sectional view of the periphery of another embodimentof a permanent magnet electric rotating machine according to the presentinvention;

FIG. 7 is a cross-s-ctional view of the periphery of a rotor of anotherembodiment of the permanent magnet electric rotating machine accordingto the present invention;

FIG. 8 is a cross-sectional view of the periphery of a rotor of afurther embodiment of a permanent magnet electric rotating machineaccording to the present invention;

FIG. 9 is a cross-sectional development view of the periphery of a rotorof a further embodiment of a permanent magnet electric rotating machineaccording to the present invention;

FIG. 10 is a cross-sectional development view of the periphery of arotor of a further embodiment of a permanent magnet electric rotatingmachine according to the present invention;

FIG. 11 is a cross-sectional development view of the periphery of arotor of a further embodiment of a permanent magnet electric rotatingmachine according to the present invention;

FIG. 12 is a cross-sectional view of the periphery of a rotor of afurther embodiment of a permanent magnet electric rotating machineaccording to the present invention;

FIG. 13 is a perspective view showing a magnetic pole supporting membershown in FIG. 12;

FIG. 14 is an axial direction cross-sectional view showing the permanentmagnet electric rotating machine shown in FIG. 12;

FIG. 15 is a cross-sectional view of the periphery of a rotor of afurther embodiment of a permanent magnet electric rotating machineaccording to the present invention; and

FIG. 16 is a cross-sectional view showing a rotor of a furtherembodiment of a permanent magnet electric rotating machine according tothe present invention.

DESCRIPTION OF THE INVENTION

Hereinafter, one embodiment of a permanent magnet electric rotatingmachine according to the present invention and an electromotive vehicleusing a permanent magnet electric rotating machine according to thepresent invention will be explained in detail referring to figures.

FIG. 1 is a cross-sectional view of the periphery of one embodiment of apermanent magnet electric rotating machine according to the presentinvention having an inner rotor and a concentrated winding statorstructure.

A permanent magnet electric rotating machine is constituted by a stator1 and a rotor 2. The stator 1 and the rotor 2 are arranged with arotation air gap formed between one another as shown in FIG. 1.

The stator 1 comprises a stator iron core 3 and a stator winding 4. Thestator iron core 3 comprises a core portion 5 and a stator salient poleportion 6. In the core portion 5, a magnetic circuit is formed so topass a magnetic flux to the stator salient pole portion 6. In thisstator salient pole portion 6, the stator winding 4 is wound round in aconcentrated manner.

The rotor 2 comprises a shaft 7, a rotor iron core 8 and pluralpermanent magnets 9. In the rotor iron core 8, plural permanent magnetinsertion holes 10 in which are inserted the permanent magnets 9 andholes through which the shaft 7 passes are punched out in an axialdirection. The permanent magnets 9 are inserted in and fixedrespectively to the permanent magnet insertion holes 10. The shaft 7 isinserted in and fixed to the shaft passing-through holes.

As stated in the above, this embodiment of the permanent magnet electricrotating machine according to the present invention is a permanentmagnet embedded structure electric rotating machine. By arranging thepermanent magnets 9 around the rotor 2 in a ring-like form, a memberformed between the adjacent permanent magnet insertion holes 10 canfunction as an auxiliary magnetic pole 16. Namely, the permanent magnets9 are arranged separately and equally around the circumference at thesame distance in the respective permanent magnet insertion hole 10 ofthe rotor 2.

In other words, a control apparatus (not shown in the figure) cancontrol a composite force of an armature electromotive force accordingto the stator winding 4 so as to direct toward a side of a rotationdirection but not direct toward a side of a central position directionof the auxiliary magnetic pole 16.

Accordingly, a magnetic flux generated from the stator winding 4 passesthrough the permanent magnets 9 and the auxiliary magnetic poles 16. Areluctant torque is then generated. This is effective in particularduring a low speed operating condition of the permanent magnet electricrotating machine. And further since the above stated reluctant torque isadded to an ordinary torque according to the permanent magnets 9, a hightorque for an electric motor, for example, can be obtained.

FIG. 3 is a cross-sectional structure at an axial direction showing oneembodiment of a permanent magnet electric rotating machine according tothe present invention.

The stator 1 is fixed to an inner peripheral surface of a housing 11 andthe shaft 7, which is inserted in and fixed to the rotor 2, can rotatefreely with a rotation air gap against the stator 1. Further, the shaft7 is contacted and held by bearing members 13 and end bracket members12.

In the above described embodiment of the permanent magnet electricrotating machine according to the present invention, as to a materialfor the rotor iron core 8, the invention employs a rotor iron core 8having a higher magnetic permeability than a magnetic permeability ofthe permanent magnet 9, for example using a stator iron core 8 having ahigh magnetic permeability such as a silicon steel plate.

Since the rotor iron core 8 having the above higher magneticpermeability is employed in the permanent magnet electric rotatingmachine, it is possible to lessen an eddy current loss which isgenerated in an interior portion of the permanent magnet 9. Further, theiron core 8 can function effectively with the above stated auxiliarymagnetic pole portion 16.

Further, the present invention can apply to a generator and an electricmotor, an inner rotor type and an outer rotor type permanent magnetelectric rotating machine, a rotary type and a linear type permanentmagnet electric rotating machine, and a concentric winding statorstructure and a distributed winding-stator structure permanent magnetelectric rotating machine. The same effects described above can beobtained.

In this embodiment of the permanent magnet electric rotating machineaccording to the present invention, a magnetic gap 14 is providedbetween the permanent magnet 9 and the auxiliary magnetic pole portion16 which is provided adjacent to the permanent magnets 9 around theperiphery.

FIG. 2 is an enlarged view showing a surrounding portion of an optionalpermanent magnet 9 of the permanent magnet electric rotating machineshown in FIG. 1.

As shown in FIG. 2, the permanent magnet insertion hole 10 is formed soas to provide the magnetic gap 14 at a peripheral end portion of thepermanent magnet 9 and the permanent magnet 9, is inserted and fixed tothe permanent magnet insertion hole 10. This magnetic gap 14 extends inthe axial direction and contacts both the permanent magnet 9 and theauxiliary magnetic pole portion 16.

The functions of the magnetic gap 14 will be explained referring to FIG.4A, FIG. 4B and FIG. 5A and FIG. 5B.

FIG. 4A and FIG. 5A show a cross-sectional view of the surroundingportion of the permanent magnet 9 of the permanent magnet electricrotating machine, respectively. FIG. 4B and FIG. 5B show a relationshipof a magnetic flux density distribution which is generated from theperipheral surface of the rotor 2 according to the permanent magnetelectric rotating machine, respectively.

FIG. 4A and FIG. 4B show the rotor of the above stated embodiment of thepermanent magnet electric rotating machine according to the presentinvention and FIG. 5A and FIG. 5B show a rotor of the permanent magnetelectric rotating machine according to the prior art, respectively.

In both the rotors according to the present invention and the prior art,the magnetic pole piece portion 15 of the rotor iron core 8 functions asa member for transmitting the magnetic flux which is generated by thepermanent magnets 9 to the stator 1. A member between the adjacentpermanent magnet insertion holes 10, namely an auxiliary magnetic poleportion 16 in the figures functions as an auxiliary magnetic pole forgenerating a reluctance torque.

Each of the graphs shown in FIG. 4B and FIG. 5B indicate the magneticflux density distributions which are generated at the stator sidesurface (the outer peripheral surface of the rotor 2) of the rotor 2,respectively. In both figures, at the magnetic pole pieces 15, themagnetic flux which is generated from the permanent magnets 9 indicatessubstantially constant magnetic flux density distributions.

On the other hand, at the auxiliary magnetic pole portions 16, themagnetic flux from the permanent magnets 9 is barely transmitted and themagnetic flux which is generated from the stator side surface (the outerperipheral surface of the rotor 2) of the rotor 2 becomes substantiallyzero.

However, in the conventional rotor of the permanent magnet electricrotating machine, as shown in FIG. 5A, since the permanent magnet 9 isarranged to be embedded in the entire permanent magnet insertion hole10, at a boundary portion between the magnetic pole piece portion 15 andthe auxiliary magnetic pole portion 16, an abrupt change in the magneticflux density distribution appears as shown in FIG. 5B.

In the permanent magnet electric rotating machine, regardless of theexistence of the electric power supply to the electric rotating machine,since the permanent magnet always generates the magnetic flux, the rotoralways receives a force in response to a positional relationship betweenthe stator salient pole portions 6 and the magnetic pole piece portions15.

When the rotor rotates, since the position between the stator salientpole portion 6 and the magnetic pole piece portion 15 changes, a forcefor receiving the rotor 2 changes in a pulsed manner and this changeappears as the cogging torque and the torque pulsation. The more abruptthe change of the magnetic flux density distribution at the rotorperipheral direction, the greater the torque pulsation that appears.

In accordance with the reasons stated above, by providing the magneticgap 14 as shown in this embodiment of the permanent magnet electricrotating machine according to the present invention, the change of themagnetic flux density distribution can be performed gradually.

A bridge portion 17 is formed between the auxiliary magnetic poleportion 16 of the surface of the rotor 2 and the magnetic pole pieceportion 15, and also a distance is provided between the magnetic polepiece portion 15 and the auxiliary magnetic pole portion 16.

Accordingly, as shown the graph shown in FIG. 4B, the change of themagnetic flux density distribution according to the present inventionappears gradually in comparison with the change of the magnetic fluxdensity distribution shown in FIG. 5B according to the prior art.Therefore, in the present invention, the cogging torque and the torquepulsation of the permanent magnet electric rotating machine can berestrained.

Further, in the permanent magnet electric rotating machine in which therotation direction is determined to be in only one direction, themagnetic gap 14 may be provided only at one peripheral end of thepermanent magnet 9.

Further, in the embodiment of the permanent magnet electric rotatingmachine according to the present invention, a rectangularly shapedpermanent magnet 9 is used. However, the invention can employ apermanent magnet electric rotating machine having other shapes for thepermanent magnets, for example, an arc shaped permanent magnet in whichthe magnetic gap 14 is formed and a trapezoidal shaped permanent magnetin which the magnetic gap 14 is formed.

In the permanent magnet electric rotating machine comprised of the othershapes similar effects are obtained in this embodiment of the permanentmagnet electric rotating machine according to the present invention.

Other embodiments of the permanent magnet electric rotating machineaccording to the present invention will be explained referring to FIG. 6to FIG. 8.

In the embodiment of the permanent magnet electric rotating machineshown in FIG. 6 and FIG. 7, the shape of the magnetic gap 14 is variedwith respect to the shape of the magnetic gap 14 of the above describedembodiment of the permanent magnet electric rotating machine shown inFIG. 2.

In the embodiment of the permanent magnet electric rotating machineshown in FIG. 6, an indented portion is provided at a bottom portion ofthe permanent-magnet insertion hole 10, and the permanent magnet 9 isarranged in this indented portion and is installed in a stable manner.As a result, the thickness of the magnetic gap 14 along a radialdirection is made thinner than a thickness of the permanent magnet 9along its radial direction.

As shown in FIG. 6, a face of the magnetic gap 14 which faces the stator(an inner peripheral side of the rotor) is formed differently from astator side face (an outer peripheral side of the rotor) in comparisonto the face of the permanent magnet 9 which faces away from the stator.

With the above described structure of the permanent magnet electricrotating machine according to the present invention, the permanentmagnet 9 can be positioned suitably to a predetermined position of thepermanent magnet insertion hole 10.

Further, to determine the position of the permanent magnet 9, anon-magnetic material member is arranged to fill-up the magnetic gap 14,even in this case the similar effects described for the above embodimentcan be obtained. For example, a solid body comprised of a non-magneticmaterial member is arranged in the magnetic gap 14, and using a resinmember and an adhesive agent the solid body is fixed integrally to thepermanent magnet 9, accordingly the permanent magnet 9 can be stablyarranged.

Further, in the embodiment of the permanent magnet electric rotatingmachine according to the present invention shown in FIG. 7, acircumferential direction width of the magnetic gap 14 facing the statorside (the outer peripheral side of the rotor) is made larger than thewidth of the magnetic gap 14 at the face away from the stator side (theinner peripheral side of the rotor).

In FIG. 7, in particular, a circumferential cross-section of themagnetic gap 14 is formed with a substantial triangular shape. With theabove stated permanent magnet electric rotating machine structureaccording to the present invention, the magnetic flux passing-throughthe auxiliary magnetic pole portions 16 can circulate smoothly aroundthe permanent magnets 9, therefore the permanent magnet electricrotating machine having a large reluctance torque can be obtained.

Further, in the embodiments of the permanent magnet electric rotatingmachines according to the present invention shown in FIG. 6 and FIG. 7,the face of the magnetic gap 14 at the stator side is formedsubstantially in parallel to the surface of the rotor 2 at the statorside.

With the above stated permanent magnet electric rotating machinestructures according to the present invention, the magnetic saturationof the bridge portions 17 proceeds easily, according to the magneticflux generated from the permanent magnets 9 through the magnetic polepiece portions 15 and the bridge portions 17, the magnetic flux leakagedue to the auxiliary magnetic pole portions 16 can therefore berestrained.

In the embodiment of the permanent magnet electric rotating machineaccording to the present invention shown in FIG. 8, to obtain thesimilar structure shown in the above stated embodiments, in reversal theshape of the rotor 2 is varied or modified. Namely, the bridge portion17 having an inclined face 14 b is constructed to extend substantiallyvertically against an inclined face 14 a of the magnetic gap 14.

With the above stated structure permanent magnet electric rotatingmachine, since an inclination of the bridge portion 17 against theradial direction of the rotor 12 becomes large, a centrifugal forceoperating on the magnetic pole piece portion 15 and the permanent magnet9 can be supported according to a tensile force of the bridge portion17.

In general, the durability of the material of the permanent magnetelectric rotating machine is higher at the tensile force than at ashearing force. The durability against the centrifugal force in thisembodiment becomes high in comparison with the above stated embodimentof the permanent magnet electric rotating machine in which the bridgeportion 17 is positioned substantially at a right angle to the radialdirection of the rotor 2.

Accordingly, by forming a thinner bridge portion 17, it is possible toincrease the amount of the effective magnetic flux which is generated inthe permanent magnet 9, and further it can rotate the rotor 2 at a highspeed.

Further embodiments of the permanent magnet electric rotating machinesaccording to the present invention will be explained referring to FIG. 9to FIG. 11.

In the embodiments of the permanent magnet electric rotating machinesaccording to the present invention shown in FIG. 9 to FIG. 11, themagnetic gap 14 is provided between the magnetic pole piece portion 15and the auxiliary magnetic pole portions 16. As shown in the figures,the magnetic gap 14 is formed at both ends of the magnetic pole pieceportions 15.

The magnetic gap 14 extends along in the axial direction from an edgeportion of the stator side peripheral direction of the permanent magnet9. By providing this magnetic gap 14, the bridge portion 17 as shown inthe figures is formed and the magnetic flux at the bridge portion 17changes gradually, as a result it is possible to restrain the coggingtorque.

In those embodiments of the permanent magnet electric rotating machinesaccording to the present invention, the magnetic gap 14 contacts theperipheral direction of face of the stator side of the permanent magnet9, and further this magnetic gap 14 is formed to get into an innerportion side than a side of the peripheral direction end face of thepermanent magnet 9.

Further, in the permanent magnet electric rotating machine structureaccording to the present invention shown in FIG. 10, the magnetic gap 14is formed to extend toward an inner portion side of the permanent magnet9, and in the permanent magnet electric rotating machine structure shownin FIG. 11, the magnetic gap 14 is formed to extend in a rectangularshape toward an inner portion side of the permanent magnet 9.

With the above stated permanent magnet electric rotating machinestructures according to the present invention, the magnetic flux leakageto the auxiliary magnetic pole portion 16 can be decreased, the magneticdensity at the magnetic pole piece portion 15 is increased, andaccordingly the efficiency of the permanent magnet electric rotatingmachine can be increased.

Further embodiments of the permanent magnet electric rotating machinesaccording to the present invention will be explained referring to FIG.12 to FIG. 14.

In the case where the rotor comprised of the permanent magnet embeddedtype structure permanent magnet electric rotating machine rotates at ahigh speed, the centrifugal forces affecting the permanent magnet 9increase and also the burden of the member for supporting the permanentmagnet 9, namely the burdens on the magnetic pole piece portion 15 andthe bridge portion 17 increase.

In a case where in response to the above burden a thick supportingmember of the permanent magnet electric rotating machine is provided,the distance between the surface of the rotor 2 and the permanent magnet9 becomes large and the magnetic flux thus leaks to the auxiliarymagnetic pole portion 16. As a result, problems arise in that themagnetic flux transmitted from the permanent magnet 9 to the stator 1decreases and also the torque decreases.

For the above given reasons, at the peripheral direction of both ends ofthe permanent magnet 9 at the face of the stator side, as shown in thecross-sectional view of FIG. 12, the magnetic gap 14 is formed to extendto the axial direction. Further, to sandwich or to form the magnetic gap14, a magnetic pole piece supporting member 18 is inserted at the axialdirection and fixed to the magnetic pole piece portion 15 and theauxiliary magnetic pole portion 16.

FIG. 13 shows one example of the magnetic pole piece supporting member18. The magnetic pole piece supporting member 18 is comprised of amember of a nonmagnetic resin material member having a U-shape and hasan inner hollow portion. A lateral direction width of the inner hollowportion of the magnetic pole piece supporting member 18 corresponds to alateral direction width of the magnetic gap 14.

FIG. 14 is an axial direction cross-sectional view showing the permanentmagnet electric rotating machine having the rotor 2 in which themagnetic pole piece supporting member 18 is inserted from both sides ofthe magnetic pole piece portion 15 and the auxiliary magnetic poleportion 16.

Herein, the magnetic gap 14 restrains the magnetic flux which leaks fromthe magnetic pole piece portion 15 to the auxiliary magnetic poleportion 16. The magnetic pole piece supporting member 18 operates as amedium body for supporting a centrifugal force of the permanent magnet 9given on the magnetic pole piece portion 15 and a centrifugal force ofthe magnetic pole piece portion 15 itself according to the auxiliarymagnetic pole portion 16. As a result, the supporting force of thepermanent magnet 9 against the centrifugal force can be increased.

Further, after assembling the rotor 2, by cutting the bridge portion 17shown in FIG. 12 and further by maintaining the supporting force of themagnetic pole piece portion 15 according to the magnetic pole piecesupporting member 18, the leakage magnetic flux according to the bridgeportion 17 can be decreased.

A further embodiment of the permanent magnet electric rotating machineaccording to the present invention will be explained referring to FIG.15.

In this embodiment of the permanent magnet electric rotating machine, asshown in FIG. 15, the magnetic gap 14 is provided between the magneticpole piece portion 15 and the auxiliary magnetic pole portion 16. Apermanent magnet supporting member 19 is provided between the permanentmagnets 9. The magnetic pole piece portion 16 and this permanent magnetsupporting member 19 are formed by assembling a magnetic material member19 a and a non-magnetic material member 19 b.

The permanent magnet supporting member 19, as shown in figure, iscomprised of an assembling member of the magnetic material member 19 aand the nonmagnetic material member 19 b. The magnetic material member19 a and the non-magnetic material member 19 b are joined according to atype of welding process etc.

The magnetic material member 19 a is constituted by the magneticmaterial member to transmit the generated magnetic flux of the permanentmagnet 9 to the magnetic pole piece portion 15. On the other hand, thenonmagnetic material member 19 b is constituted by the nonmagneticmaterial member to restrain the leakage magnetic flux from the permanentmagnet 9 to the auxiliary magnetic pole portion 16.

With the above described permanent magnet electric rotating machinestructure according to the present invention, since the centrifugalforce upon the permanent magnet 9 is supported by the auxiliary magneticpole portion 16 through the permanent magnet supporting member 19, onlythe centrifugal force of the magnetic pole piece portion 15 acts on thebridge portion 17. Accordingly, a length of the bridge portion 17 at theradial direction can be shortened and further the magnetic flux leakagefrom the permanent magnet 9 can be lessened.

Besides, in the embodiments of the permanent magnet electric rotatingmachine structures shown in FIG. 9 to FIG. 11, it is effective toarrange or fill up a non-magnetic material member.

The thickness of the magnetic pole piece portion 15 is set to athickness necessary to obtain sufficient magnetic flux. The magnetic gap14 is punched out at the stator side of the permanent magnet 9 with theshapes as shown in FIG. 9 to FIG. 11 and in this magnetic gap 14 anon-magnetic material member, for example such as an adhesive agent anda resin member, is filled up.

With the above stated permanent magnet electric rotating machinestructure according to the present invention, without the thickthickness of the magnetic pole piece portion 15 at the radial direction,the centrifugal force received by the permanent magnets 9 and themagnetic pole piece portions 15 can be supported by the magnetic gap 14.

Further, as the material for the permanent magnet 9, it is possible toemploy a resin mold type magnet. In this case, in replacement of thenon-magnetic material member for filling up the magnetic gap 14, theresin mold type magnet can be inserted having a shape suitable for boththe permanent magnet insertion hole 10 and the shape of the magnetic gap14.

In other words, to a plastic magnet itself it is possible to serve theabove stated role by the magnetic gap 14. Further, as shown in FIG. 16,it is effective to provide a larger peripheral direction width (θa) ofthe auxiliary magnetic pole portion 16 than the peripheral directionwidth (θm) of the permanent magnet 9.

With the above stated permanent magnet electric rotating machinestructure according to the present invention, the weight of thepermanent magnet 9 for producing the centrifugal force given on thebridge portion 17 is lessened and the thickness of the bridge portion 17can be made thinner, accordingly the leakage magnetic flux leaking fromthe magnetic pole piece portion 15 to the auxiliary magnetic poleportion 16 can be decreased.

Further, since the peripheral direction width of the permanent magnet 9can be made thinner, the magnetic flux generated by the permanent magnet9 decreases. However, the reluctance torque according to the auxiliarymagnetic pole portion 16 increases relatively. This fact is effective touse a high cost neodymium magnet as the permanent magnet 9.

As a compensation in order to lower the cost, the size of the permanentmagnet 9 can be decreased according to the reluctance torque of theauxiliary magnetic pole portion 16, thus an improvement in the costperformance of the permanent magnet electric rotating machine can beattained.

Further, by applying the permanent magnet electric rotating machinedescribed above to an electromotive vehicle, in particular to anelectric vehicle, since the cogging torque can be small, it can mount astable permanent magnet electric rotating machine drive apparatus whichcan start smoothly. As a result, the electric vehicle having a longrunning distance per one time charging or having a small consumption ofelectric power can be provided.

According to the present invention, the permanent magnet electricrotating machine having a small torque pulsation can be constituted.Further, according to the present invention, it is possible to set thepositioning of the permanent magnet of the permanent magnet electricrotating machine.

According to the present invention, in the permanent magnet electricrotating machine it is possible to circulate smoothly the magnetic fluxpassing-through the auxiliary magnetic pole portion around the permanentmagnet. Further, in the permanent magnet electric rotating machine it ispossible to restrain the magnetic flux leakage from the member of thestator side of the magnetic gap in the permanent magnet to the auxiliarymagnetic pole portion.

According to the present invention, the permanent magnet electricrotating machine having the small torque pulsation can be realized.Further, according to the present invention, it is possible to restrainthe magnetic flux leakage from the permanent magnet at the face of thestator side to the auxiliary magnetic pole portion of the permanentmagnet electric rotating machine.

According to the present invention, it is possible to secure thesupporting force against the centrifugal force acting on the permanentmagnet of the permanent magnet electric rotating machine. Further,according to the present invention, an electromotive vehicle, which iscomprised of the permanent magnet electric rotating machine, having thesmall cogging torque and having the stable drive apparatus, can beprovided.

1. A permanent magnet electric rotating machine, comprising: a stator;and a rotor arranged opposite said stator with an air gap; said rotorhaving a rotor core and plural permanent magnets embedded in said rotorcore; plural permanent magnet insertion holes, auxiliary magnetic polepiece portions for generating a reluctant torque, magnetic pole pieceportions for transmitting a magnet flux of said permanent magnet to aside of said stator, bridge portions for connecting between saidmagnetic pole piece portions and said auxiliary magnetic pole pieceportions, and magnetic air gaps are formed in said rotor core; whereinto form said magnetic pole piece portions in said side of said stator,said permanent magnet insertion portions are formed in said rotor core,and said permanent magnet insertion portions are arranged with aring-shape in an internal portion of said rotor core; said permanentmagnets are inserted into said permanent magnet insertion holesalternatively with a reversed polarity, and said permanent magnets arearranged in said internal portion of said rotor core; said auxiliarymagnetic pole piece portions are formed between adjacent permanentmagnets in a peripheral direction, said bridge portions are arrangedbetween said magnetic pole piece portions and said auxiliary magneticpole piece portions, and said bridge portions are formed in accordancewith a formation of said magnetic air gaps; said magnetic air gaps areformed in said internal portion of said rotor core, and said magneticair gaps are formed between said magnetic pole piece portions and saidauxiliary magnetic pole piece portions, thereby a change of a magneticflux density distribution of said permanent magnets between saidpermanent magnets and said auxiliary magnetic pole piece portions isformed smoothly; and further said magnetic air gaps extend over fromboth end portions of said magnetic pole piece portions to said side ofsaid stator, and lengths in radial directions of said bridge portionsare formed short, thereby a leakage of a magnetic flux of said permanentmagnets from said magnetic pole piece portions to said auxiliarymagnetic pole piece portions through said bridge portions is restrained.